Study Design and Participants

A retrospective observational study was carried out on patients with suspicion of NTMPD admitted to the First Affiliated Hospital, School of Medicine, Zhejiang University, from March 2021 to October 2022. The inclusion criteria were as follows: (1) patients aged over 18 years; (2) patients who visited the First Affiliated Hospital, School of Medicine, Zhejiang University, from March 2021 to October 2022; (3) patients with pulmonary lesions in accordance with the imaging changes of NTMPD, including thin-walled cavities, multifocal bronchiectasis, multiple nodules, and mass shadow; (4) patients with one or more positive AFS results in sputum or BALF, but no response to regular antituberculosis therapy; and (5) patients with persistent symptoms (for example fever, respiratory symptoms) that did not respond to traditional anti-bacterial therapy. Exclusion criteria were as follows: (1) patients with incomplete clinical data; (2) patients without mNGS or culture on bronchoalveolar lavage fluid (BALF). The enrollment and screening process of patients is displayed in Figure 1. The NTMPD group was confirmed according to the guidelines of the American Thoracic Society/European Respiratory Society/European Society of Clinical Microbiology and Infectious Diseases/Infectious Diseases Society of America (ATS/ERS/ESCMID /IDSA) (2020).¹⁴ In the suspected-NTMPD group, the patients met the clinical and radiographic criteria of ATS/ERS/ ESCMID/IDSA guidelines, and the mNGS results in BALF was positive, which met the diagnosis criteria of NTMPD in the guidelines formulated by the Chinese Medical Association,¹⁵ but not the guidelines of ATS/ERS/ ESCMID/IDSA. The patients in the non-NTMPD group did not meet the ATS/ERS/ ESCMID/IDSA or Chinese guidelines.

Flowchart of patient enrollment and grouping.

Data were extracted from the electronic patient record system of the hospital and the results of AFS, conventional culture, and mNGS in BALF of all patients were collected. This study complied with the Declaration of Helsinki and was approved by the Ethics Committee of the First Affiliated Hospital of Zhejiang University. Due to the retrospective nature of the study and as no identifiable patient information was included in this manuscript, the need for consent was waived.